Refrigerating system



Nov. 2, 1937. w. J. BoLToN REFRIGERATING SYSTEM am, mm, w Nm, ww, um wvmv Nov. 2, 1937. w. .1. BoL'roN 2,097,685

REFRIGERATING SYSTEM Filed April 28, 1953 2 Sheets-Sheet 2 Batented Nov. 2, 1937 UNITED STATES PATENT OFFICE' Raiuno.lsznlrrnw srsnnr wmum J. nunon, Pittsburgh, n.

Applicationapru za, im, sensi No. sssaa 19 omnia. (ci. ca -91.5)

My invention relates to a system of refrigeration, and more particularly to an improved method and apparatus for utilizing as a refrigerant, solidified carbon dioxide (CO2) commonly vre- 5 ferred to as dry ice, or extremely cold materials of that character having the property of changing from a solid to a gaseous state and absorbing both latent and sensible heat during the process of such change.

As heretofore practiced, systems of this type have been found to be relatively ineillcient and expensive to operate'. This has been due in the most part to their inability to emciently utilize the full refrigerating capacities of the dry ice,

and it has militated considerably against their success. One of the chief difficulties has been their inability to utilize, with any great degree of eiciency, the cold contained in the gas or vapor evolved as the ice is melted. lSuch gas is evolved at a very low temperature and represents a very considerable percentage of the refrigerating capacity ofthe ice. In many systems this gas is completely wasted by being allowed to escape as it is formed. In others, various methods are resorted to in an eiort to recover this cold, but with no degree of success comparable with that of this invention.

Another serious objection to the prior systems is their inability to produce what may be termed high speed refrigeration. In addition,

they leave much to be desired in the way of satisfactory control over the refrigeration which they produce. i

With these and various other diiliculties of thev prior systems in' mind, it is among the objects of my invention to provide an improved method and system of refrigeration in which dry ice is used as a refrigerant, and in which the maximum refrlgerating capacity of the ice, including that of the C02 vapor produced as the ice is melted, is utilized.

Another object is to provide a system of this character, which is capable of efnciently producing refrigeration at an extremely rapid rate.

45 It is also an object to provide in a system of this character for effectively and automatically controlling the refrigeration, and for doing so in such a way as to provide a most eiilclent consumption of the refrigerant.

50 A further object is to provide for' circulating a heat-conducting liquid or brine into the regions to be refrigerated and for using the gas evolved by the sublimation of the ice for positively circulating such liquid.

55 A stm further and highly important object of my invention is to provide a refrigerating system hembodying the aforementioned features which is relatively simple to manufacture and both dependable and comparatively inexpensive to operate. 5

'Ihese and numerous other objects as well as the various other novel features and advantages of the invention will be apparent when the following detailed description is read in conjunction with the accompanying drawings in which 10 Fig. 1 is a view partly in section and partly in elevation of refrigerating system constructed in accordance with the invention; Fig. 2 a plan view ofthe circulating coil disposed in the ice tank of the system shown in Fig. 1; Fig. 3 a view similar to Fig. 1 of a modification of the invention, and Fig. 4 a similar view of another modication.

The invention is predicated to a considerable extent upon my discovery of the ability which 20 certain light petroleum or hydrocarbon liquids such as gasoline. naphtha, and kerosene, which remain fluid at the temperature of dry ice, have, even at atmospheric pressures, for absorbing or dissolving enormous quantities of carbon dioxide 25 vapor as it is liberated from its solid state. I have found that when a piece of dry ice is placed in one of these liquids, and the invention contemplates all liquids having similar properties,

that the liquid completely wets the ice even to 30 penetrating its pores, and that the gas produced by the sublimation of the ice is absorbed or dissolved in the liquid at a rapid rate which varies inversely as the temperature of the liquid; also that the absorbed gas is not liberated by the 35 liquid once it is chilled until it comes in contact with a surface or atmosphere having a temperature which is higher than that of the solution, and when so released it has a temperature approximating that of the medium which causes 40 its release. In other words, the gas is not released from the solution until it has produced substantially all of the useful refrigeration itis capable of producing.

In addition, I have found that such liquids provide a most excellent heat-conducting medium, and that due to their ability to wet the ice, which they do by coming in intimate contact with the ice crystals, they are able to transmit the latent heat required for the sublimation of the ice to the ice at a very rapid rate, making it possible to produce refrigeratiorilat an extremely high rate. The advantages of this feature will be more fully appreciated when it is considered that in all .the prior systems the ,gas evolved by the melting of the ice is, to the best of my knowledge, permitted to form a barrier between the ice and the medium used to conduct the heat from the region being refrigerated to it, and as such gas has extremely high insulating properties, `it greatly retards the heat flow. For example, in most systems the ice is placed directly on a solid heat-conducting surface. No matter what force is applied to it, the gas evolved forms a wall or insulating cushion between the ice and such surface. 'I'his same condition is established when the ice is immersed in most liquids, and as a result a large percentage of the refrigerating ability of the ice is lost in the vapor which is permitted to escape, and heat transfer to the ice is retarded by the poor conductivity at the qpoint of contact.

After the CO: vapor is released from the heatconducting liquid where substantially all of its useful refrigeration properties are extracted, I utilize it to improve the insulation of the tank in which the dry ice is housed, and when a secondary circulating system is empio ed, I also utilize it to positively force the circ ating brine through such system.

Referring to the drawings by way of illustrating the invention, and first to Figs. l and 2, the numeral I designates a tank in which there is provided a quantity 2 of gasoline or some other.

liquid having the aforementioned properties with respect to CO2. In this bath the dry ice l is placed and, while articles to be refrigerated may be placed directly in the bath, the present system contemplates the use of a secondary circulating system for cooling the regions to be refrigerated. Such a circulating system, as shown, is made up principally :of a circulating tank coil 4 which is arranged in the bottom of the ice tank I, and one or more cooling coils, 5 and 6, which are arrangedin the region to be refrigerated and connected to the first-mentioned coil. A power unit 1 is included in this circuit and utilized to positively effect the circulation of the brine used in such system, which may be alcohol or some similar `liquid .having the ability to remain fluid a low, temperatures. v

To' provide the circulating brine with sumcient opportunity to be chilled when it passes through the ice tank, the circulating coil 4, as shown in 'Figs. 1 and 42, is provided with a considerable length and is completely immersed in the ice bath 2. Furthermore, to insure the ice settling substantially uniformly into the bath which, as will be appreciated, is desirable, the coil is made flat and arranged in the tank I directly below the ice. To increase its length and conserve space, the coil illustrated is made up of a pair of headers 6 and 9 having a series of substantially w-shaped nested sections 4a disposed in a horizontal plane connected to them. From one of these. a pipe II forming an outlet connection is extended through the side of the ice tank I and connected by a pipe I3 with the cooling coils 6 and 6. From the other, an inlet pipe I2 is extended through the sidetank I and connected by a pipe I4 to the power unit 1.

The power unit in this particular embodiment, although it may take other forms, is designed to be operated by gas pressure produced by the sublimation of the dry ice in the refrigerating tank I. To captivate the CO: gas for this purpose a lid I8 is provided and secured in the opening I! through which the ice is fed into the tank I, such lid being preferably arranged to ilt in the opening from the inside of the tank so that the gas pressure so established will assist a series ci' bolts 2I in holding the lid in place. For conducting the pressure so developed to the power unit, a pipe 22 is connected to it and to the tank I at a point well above the level of the refrigerating bath 2. To control the flow of gas to the power unit and the pressure therein for controiling the brine i'low, a relief valve 2i of any suitable construction is placed in the pipe 22, although preferably an adjustable valve is provided so that the pressure in the power unit may be varied. To indicate the pressure so supplied, a pressure gauge 20 is connected in the power unit end of pipe 22.

In detail, the power unit illustrated comprises a main tank 24 which is divided in three compartments 2B, 26 and 21 arranged one below the other, and separated by horizontal partitions 28 and 26. The upper end of the upper, 25. of these compartments is connected by a pipe I5 to the outlet ends of the cooling coils 5 and 6. The lower'one, 21, in turn is connected, as previously described, by a pipe I4 to the inlet header 9 of the refrigerating coil 4.. disposed on the ice tank I. For discharging the brine or circulating liquid from the upper compartment 25 into the center compartment 26 a goose neck outlet fitting II is mounted on the underside of the upper partition 28, and to control the flow of the brine through this outlet a hinged gravity closed lid 62 is provided on its upturned lower end. A similar outlet fitting Il provided with a lid 64 is mounted in the lower partition 28 for controlling the now of the brine from the intermediate compartment 2B into the lower compartment 21.

To carry out the operation of the power unit, the pipe 22 leading to it from the ice tank I is divided into two branches 22a and 22b, which are connected respectively to the lower compartment 21, and through a valve casing 3S to the intermediate compartment 26. In this latter valve casing there is arranged a valve 36 which is disposed to seat in the lower end of the casing and is utilized for controlling the gas flow into the middle compartment. To control its operation it is attached to a lever 21 which is pivotally attached at one end to the wall of the center compartment 26 and at the other end to one end of a pressure spring 66 which is connected to one end of a toggle lever 69 that is pivotally mounted in a support 4I suspended from the upper partition 26. 'I'he other end of such toggle lever 39 is connected to a float 42 used to determine the operation of the valve 66, being arranged to ride on the liquid contained in the intermediate compartment 26. It also controls a second valve 43 mounted on the valve lever 61 which is adapted to seat at the lower end of a pipe 44 connected between the top of the intermediate compartment 26 and the top of the upper compartment 26. This latter valve 43 is so mounted that it is closed when the first-mentioned valve 36 is open, and vice ver: a. With such a construction, as will be appreciated, when float 42 is in its lower position, due to spring 8.6 being under compression, it will hold valve 36 closed, and valve 43 open. When, however, the float 42 raises sufficiently to move theend of the toggle lever 39 past the center of the adjacent end of the toggle spring 38, the spring will snap valve 43 closed and valve 36 open. This same action will take place in the reverse order as the float travels downward. To permit any gas entrapped in the brine to escape, an outlet 45,

of operation of my invention and have illustrated and'described what I now consider to represent its best embodiment. However, I desire to have it understoodthat, within the rscope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

l. A method of refrigerating which comprises bringing a quantityof solid CO2 in contact with a light petroleum liquid having theability of wetting and at relatively low pressures of absorbing the CO: vapor produced by the sublimation of the ice at a very rapid rate and of retaining said vapor in solution until it has given up to the liquid substantially all of its useful refrigeration and utilizing said liquid for absorbing heat from a region to be refrigerated.

2. A method of refrigerating which comprises bringing a quantity of solid CO2 ice in contact with a liquid having the ability to remain fluid at relatively low temperature and of both wetting the ice and absorbing CO: vapor produced by a sublimation of theice at a very rapid'rateat relatively low pressure and of retaining said vapor in solution until it has given up to the liquid substantially all of its useful refrigeration, bringing said liquid in heat exchange relation with a secondary liquid and circulating the secondary liquid in heat exchange relation with a region to be refrigerated.

3. A method of refrigerating which comprises bringing a quantity of solid CO2 ice in contact with liquid having the ability to absorb the C02` vapor produced by the sublimation of the ice at a very rapid rate and retaining said vapor in its solution until it has given up substantially all of its useful refrigeration to the liquid, bringing said liquid in heat exchange relation with a secondary liquid, circulating said secondary liquid in heat exchange relation with a region to be refrigerated, and controlling the temperature of the said latter liquid to control the temperature of the refrigerated region.

4. A method of refrigerating which comprises bringing a quantity of solid CO2 ice into heat exchange contact with a liquid having the ability to wet the ice and absorb the CO2 vapor produced by its sublimation at a very rapid rate and of retaining such vapor in solution untilit has given up substantially all of its useful refrigeration, bringing saidliquid in heat exchange relation with a secondary liquid, circulating said seconda'ry liquid in heat exchange relation with a region to be refrigerated, and utilizing the CO2 vapor released from said first mentioned liquid for positively circulating said secondary liquid.

5. A method of reirigerating which comprises bringing a quantity of solid C02 ice into direct heat exchange relation with-a liquid having the ability to wet the ice and absorb the CO2 vapor evolved by the sublimation of the ice at a very rapid rate, bringing said liquid in heat exchange relation with a secondary liquid, circulating the said secondary liquid `through a region to be refrigerated, captivating theCO: vapor released from the first mentioned liquid and utilizing the pressure released thereby for circulating the secondary liquid and controlling the flow of the secondary liquid to control the temperature of the refrigerated region.

6. A methodoi.' refrigerating which comprises bringing a quantity of C02 ice into heat exchange relation with a light hydrocarbon liquid having the abilityto remain fluid at relatively low tem- :,oomsa peratures and to wet the ice and absorb the CO vapor produced by the sublimation of the ice at a very rapid rate and to retain such vapor in solution until it has given up all of its useful refrigeration to the liquid, circulating a secondary liquid and conducting to said liquid for absorption thereby heat from a region to be refrigerated. 7. A refrigerating apparatus comprising a tank forming a heat-absorbing and heat-conducting surface containing a quantity of light petroleum liquid having the ability to wet CO2 ice and of absorbing C02 vapor produced by the sublimation of CO2 ice at a relatively high temperature and of retaining `said vapor in solution until it has given up substantially all of its useful refrigeration disposed in said tank, a quantity of CO: ice immersed in said liquid and means for utilizing the C0: vapor absorbed by said liquid after it is released for insulating said tank against refrigeration losses.

8. A refrigerating apparatus comprising a tankfor receiving a quantity of CO2 ice, a quantity of liquid provided in said tank to form a bath for the ice, said liquid having the ability to absorb the CO2 ice produced by the sublimation of said ice, means arrangedl in heat exchange relation with said liquid for circulating a secondary liquid, means for conducting the said liquid in heat exchange relation with a region to be refrigerated.' means for controlling the flow of said liquid through the said circulating liquid to control the refrigerant produced in the refrigerated region. 9. A refrigerating apparatus comprising a tank adapted to receive a quantity of solid C02 ice, a quantity of liquid provided in said tank to form a heat conducting bath for the ice, and having the ability of wetting the ice and of absorbing the CO2 vapor produced by the sublimation of the ice at a very rapid rate and of retaining said vapor in solution until it has given up to the bath substantially all of its useful refrigeration, a circulating coil mounted in said tank in 'heat exchange relation with saidliquid, a cooling coil arranged in the region of the refrigerant, means connecting said coils, brine in a circulating system formed by said circulating coil and said cooling coil, means for circulating'said brine through said circulating coil 10. A system of refrigerating which comprises a tank for receiving a quantity of solid CO2 ice, a quantity of liquid provided in said tank to form a heat conducting bath for said ice and having the ability to absorb the CO: vapor -produced by the sublimation of CO2 ice at a very rapid rate, a circulating system for refrigerating a region re- -mote from said tank comprising a coil mounted in said tank and in heat exchange relation with said liquid andconnected to a coil disposed in said region to be refrigerated, brine disposed in said coils, means for circulating -said brine through said coils, and means for controlling the said brine to control tha temperature of the refrigerated region.

11. A system of refrigeration comprising a tank for receiving a quantity of CO2 ice having a quan-` tity of liquid disposed therein to form a bath for the ice, said liquid having the abilityto wet and make direct heat exchange with said ice and to absorb the' CO2 vapors produced by the sublimation of the CO2 ice at a very rapid rate, a circulating coil mounted in heat exchange relation with said bath, a cooling coil mounted in a region to be refrigerated, means connecting said coils together, brine in said coils, and temperature responsive means for controllingthe aca/,oss

which may also be used for charging the brine into the unit, is provided in the top of the power unit.

In thev operation of the power unit 1,-if valve 43 is open and valve 36 closed, the pressure in the upper compartment 25 and the intermediate compartment 26 will be the same. Under such conditions the brine discharged from the coils 5 and 6 will flow through the outlet 3| of the upper compartment 25 into the middle compartment 26. The ,outlet 33 of this latter compartment under such conditions will be closed, due to the action of the pressure delivered to the lower compartment upon the lid 34. The pressure maintained in the lower compartment will also force the brine from such compartment 21 through the circulating coil 4, and the cooling coils 5 and 6 into the upper compartment 25.

When the oat 42 is raised sufficiently by the brine filling the intermediate compartment, it-

willso operate the toggle mechanism as to open valve 36 and close valve 43. 'I'his `will cause the pressure in middle chamber 26 to exceed that in the upper chamber 25, whereby closing the lid 32 on the outlet 3|, and to equal that in the lower chamber 21 which will allow the lid 34 on the outlet 33 to be opened by the .brine in the middle chamber 26, which then ilows into the lower chamber 21. Whenever the middle chamber is emptied, the cycle of operation is repeated.

In order to automatically regulate the refrigeration produced by the coils 5 and 6 a thermostat valve 46 may be placed in the flow lines of each of these coils to regulate the ow of the brine through them. These valves, as shown, comprise a easing which is divided by a partition 41 into an inlet compartment 48 which is connected to the discharge end of the coil and an outlet compartment 49 which is connected by the pipe l5 to the upper compartment 25 of the power unit 1. In the partition 41 there is provided a valve seat on which a valve 5| disposed to move in chamber 49 is arranged to seat. Such valve is normally urged toward its seat by a spring 62 mounted in chamber 49 for adjustment by a screw 5'3. In the inlet compartment 46 there is arranged a bellows 54 which is connected by a valve stem 55 with the valve 5|. 'Ihis bellows in turn is connected by a tube 56 to a thermal bulb 59 which is arranged in the region or compartment to be cooled. In such bellows and bulb there is placed a highly expansible uid which operates the bellows and valve 5| in response to the temperature which itencounters, and whereby the flow of the brine is automatically controlled to maintain a temperature determined by the adjustment of spring 52. control, it will be appreciated that each coll may be regulated separately of the other, and as many coils may be used as the capacity of the refrigerating tank I and coil 4 will permit.

To prevent loss of refrigeration, due to absorption of heat by the ice tank I, such tank is housed in an outer casing 6| and the space between the tank and casing is filled with some suitable insulating material, such as ground cork. To further improve this insulation the two casings and' 6I are sealed together about the opening I9 and the outlet of the relief valve 23 is connected by a pipe 62 to the compartment formed by them so that the CO2 gas exhaust from the relief valve 23 is circulated through such compartment before it is discharged into the atmosphere by way of an With this sort of I er casing 6|. Thus, the air in the ground cork, and between the walls of the tank and casing, is replaced by the excess CO2 which has avery low heat conductivity, and any useful refrigeration remaining in the gas is utilized, but more particularly, any moisture which may tend to become entrapped is excluded from the insulatln compartment.

To operate the system, a piece of ice 3 is placed in the gasoline bath 2. As soon thereafter as sufcient pressure is established to force the brinev from the lower compartment of the power unit. the circulation through the coils 4, 5 and 6 is inaugurated. When the temperature of the brine and the cooling coils approaches the temperature which it is-desired to maintain in the refrlgerated regions, the thermostats 46 come into service. These then automatically control the flow of the brine and maintain the temperature desired in such regions. As the circulation oi' the brine recedes, the temperature of the bath 2 approaches the temperature of the ice and evaporationof the ice correspondingly diminishes. Consequently, the ice is consumed in direct proportion to the refrigerating requirements, except for a very small portion which is required to dissipate the heatv absorbed by the various parts of the apparatus.

Referring to Fig. 3, an embodiment oi' the invention is illustrated in which the parts are designated by the same numerals used in Fig. l, except for the use of the sumx a. In such embodiment a vertical coil 4a is provided in the ice tank la in piace of a ilat coil, and arranged to surround the ice 3a. For circulating the brine in the cooling coils 5a an ordinary pressure ,pump 1a is employed, which, as will be appreciated, may be regulated to control the refrigeration produced by such coil 5a. With such a system the circulating brine is never brought in contact with the CO2 vapor, which is desirable. To take care of the expansion and contraction of the brine in thus circulating, a reserve tank 65 is provided,

of the pump 1a.

Referring to Fig. 4 wherein parts similar to those -shown in Fig. l are also designated by the same numerals except for the use of the sufiix b, the bath 2b is used as the brine for the circulating system, as well as a heat transferring medium for contactingthe ice. This has. the advantage that no circulating coil need be inserted in the bath 2b, but requires that the cooling coil 5b be connected directly through the pump 1b to the tank Ib. As will be readilyappreciated, the coil 5b may be also dispensed with, and the tank Ib used as the heat absorbing surface, or the bath 2b may be used for refrigerating articles by immersing them in it.

In view of the foregoing it will be readily understood by those skilled in the art that my invention may be applied to numerous domestic and commercial uses, particularly where mechanical refrigerating or electric systems are impractical and uneconomical, as they are in many places where a considerable amount of refrigeration is desired for short periods and where heavy refrigerating loads are demanded in places which do not afford sufficient space for the customary mechanical systems. Examples of such are in ice cream freezing units designed for counter service, in refrigerated trucks, railway cars, beverage dispensing apparatus, and the like.

According to the provisions of the patent statutes, I have explained the principle and mode -being connected to the pipe |4a on the inlet side circulation of said brine to control the refrigerant in said refrigerated region.

12. A' system of refrigeration comprising a tank for receiving a quantity of CO2 ice, a quantity of liquid provided in said tank to form a bath for the ice and having the ability to absorb the CO2 vapor produced by the sublimation of the ico and to retain said vapor in solution until it has given up substantially all of its useful refrigeration, a circulating system comprising a coil disposed in heat exchange relation in said bath, a coil connected thereto disposed in a region to be refrigerated, brine contained in said circulating system, and 'means operated by CO2 vapors produced by the sublimation of ice disposed in said container after it is released from said bath for circulating said brine to said circulating system.

13. A system of refrigeration comprising a tank for receiving a quantity of CO2 ice, a quantity of liquid provided in said tank to form a heat exchange bath and having the ability to Wet the CO2 ice and absorb the CO2 vapor produced by the sublimation of such ice at a very rapid rate, a circulating coil arranged in a horizontal plane in the base of said tank, a coil arranged in a region to be refrigerated, means connecting said coils together, a brine lling said coils, and means `for circulating said brine.

14. A method of refrigerating which comprises bringing a quantity of solid CO: ice in contact with a light petroleum and bringing said petroleum in heat exchange relation with a region or light petroleum disposed in said tank to form a heat exchange bath for said ice, and means for bringing said petroleum in heat exchange relation with a region to be refrigerated.

19. A refrigerating apparatus comprising a tank for receiving a quantity of CO2 ice, a quan= tity of light petroleum provided in said tank as a bath for the ice, means arranged in heat exchange relation with said petroleum for circulating a secondary liquid, means for conducting said secondary liquid in heat exchange relation with a region to be refrigerated, and means for controlling the iiow of said secondary liquid through said circulating means to control the refrigeration effected in the refrigerated region.

Y WILLIAM J. BOLTON. 

